This is a very interesting specimen with unusual "hedgehog" epididymite, a single PSM of rhabdopane-(Ce) close to brockite in composition, and several crystals of "pyrochlore" with very high Si content (see below).
Epididymite has several distinct habits at MSH. The “hedhehog” habit shown in the first pair of photos is perhaps less common than the others. The FOV is 2.0 x 2.7 mm, with individual crystals to ca 1.0 mm. This is the only “hedgehog” on the specimen. The epididymite ID was verified via PXRD (on another sample).
There is also a single crystal of rhabdophane-(Ce). The crystal is very small (0.33 mm), but it is of interest because microprobe (by Pavel Kartashov of IGEM, on another crystal) shows that it is close to brockite in composition. Brockite is very rare at MSH. (But this is NOT brockite. The composition of the “Ce site” was found to be ((Ce.28 La.16 Nd.07 Pr.03 Eu.01 Gd.01 Sm.01)sum=0.56 Ca.33 Sr.10 Ba.01)sum=1.00. So even though Ca is the single most abundant anion, the material is REE dominant, with Ce being the most abundant of the REE.)
The rhabdophane-(Ce) is shown in the second pair of photos (FOV 2.1 x 3.6 mm). It is the off white “flying saucer” sitting on aegirine at center left.
The yellowish crystals on the aegirine are “pyrocholore” with very elevated Si (see the "Analysis" tab). Initially, the Si was interpreted as “Ta”, which would make some of the samples “microlite” – a species that has not been reported from MSH. However, after consulting with a mineralogist very familiar with MSH, it was concluded that the peaks are actually Si – not Ta. Apparently “pyrochlore” at MSH sometimes has very high Si content. It is not know if this is because the crystals are metamict, or if, as suggested by some, the Si is incorporated into the pyrochlore structure. Note that the specific pyrochlore species found at MSH have not yet been sorted out, so it is labeled as “pyrochlore group”. (Since many pyrochlore species differ by having F vs OH etc. in the “Z” site, it will never be possible to determine the species via EDS in any case.)
The “pyrochlore” crystals look "fuzzy" under a scope. The next photo shows another encrusted aegerine fragment that was soaked in HCl. Most of the coating disappeared (slowly). The remaining crystals look like typical MSH “pyrochlore” – except for the yellow color. However the EDS scans for both the "fuzz" and the "naked" crystals were very similar. The "fuzzy" scan shows more Ca, perhaps indicating the presence of calcite acting as a "cement" for small grains of "pyrochlore".
The two full-view photos show the “epididymite side” and the “rhabdophane sise” resp.
The specimen is basically a large micro. It could probably be trimmed to “true” micros size without much difficulty. But the epididymite sits on colorless tabular albite, a few crystals of which are well-formed and may be of interest. Trimming the specimen would destroy at least some of the albite crystals – and fragment the aegirine cum pyrochlore.
Single item shipping weight is 3.3 oz (96g). Outside the USA, the stated postage and packing rate applies up to a total weight of 8 oz (225 g).
Within the USA, there is a nominal increase of $0.20 for each additional ounce. Above 13 oz, I will use Priority Mail. Up to 16 oz, the “own box” Priority rate is $9.25 (including packing).
